Floor joist

ABSTRACT

A truss-type floor joist formed of vertically aligned parallel chords connected together between their ends by alternating diagonal web members and at their ends by a pair of vertical end members arranged in face-to-face contact, with the chords, web members and end members all formed of 2 X 4 wood strips arranged with their narrow edges vertical. Each chord has an inner liner member in the form of a 2 X 4 wood strip member arranged in faceto-face contact therewith and extending from each end of the chord to a point just past its first, adjacent set of diagonal web members. Each of the joints formed by abutting web members and end members with the chords are overlapped on both vertical faces with metal connector plates having struck-out teeth embedded in the respective overlapped wood members.

United States Patent Schmitt [451 Mar. 28, 1972 [s41 FLOOR JOIST PrimaryExaminer-Henry C. Sutherland [72] Inventor. Jack N. Schmitt, Birmingham,Mich. Anamey cunen, Settle, Sloman & Cantor [73] Assignee: TruswalSystems, Inc., Troy, Mich.

57 ABSTRACT [22] Filed: Nov. 18, 1970 1 A truss-type floor joist formedof vertically aligned parallel [2n Appl' 90,579 chords connectedtogether between their ends by alternating diagonal web members and attheir ends by a pair of vertical 521 0.5. CI. ..52/693, 52/642, 52/730end members arranged in face-04m 60mm with 511 Int. Cl ..E04c 3/12chmds, web members and end members 2x4 58 Field of Search ..52/639 642690 693 696 StripS arranged with their edges Each 5 chord has an innerliner member in the form of a 2X4 wood strip member arranged inface-to-face contact therewith and extending from each end of the chordto a point just past its [56] References Cited first, adjacent set ofdiagonal web members. Each of the joints UNITED STATES PATENTS formed byabutting web members and end members with the chords are overlapped onboth vertical faces with metal con- 2,385,l42 9/1945 Lank ..52/639nector plates having struckout teeth embedded in the respec 2,886,8575/1959 Brosenius .....52/639 fi overlapped wood membem 3,170,198 2/1965Snider ..52/642 3,53 1,904 10/1970 Sanford ..52/642 2 Claims, 4 DrawingFigures S a f 1 a 4 /3 /4a a Patented March 28, 1972 FIG. I

mvemoa JACK N. SCHMITT ATTORNEYS FLOOR JOIST BACKGROUND OF INVENTION 1Floor joists used to support the floor in a small building, andsimilarly used to support flat roof sections, have been typically madeof large wood beams, such as 4X8 and 2X6 in cross section, oralternatively, out of metal I-beams. Suitable lumber for this purpose isrelatively expensive and difficult to obtain and process. Likewise,metal I-beams are also relatively expensive and difficult to handle andassemble into the building construction.

Thus, the invention herein relates to floor joists formed in atruss-like shape out of conventional, readily available and inexpensive2 4 wood strips which joists may then be used in small buildingconstruction such as in dwelling houses, for floor joists as well asceiling joists where appropriate.

SUMMARY OF INVENTION The invention herein contemplates forming floorjoists in a truss-like configuration out of long, parallel chords madeof conventional 2X4 lumber with the chords interconnected by alternatingdiagonally arranged 2X4 web members and vertically arranged end memberswith all joints connected together by means of conventional flat, sheetmetal connector plates which include integral struck-out teeth forembedding into the wood. Such type connector plates are illustrated forexample in the patent to Broder, US. Pat. No. 3,242,788 granted Mar. 29,1966.

More specifically, the invention herein contemplates forming theopposite ends of the chords in double thickness by means of inner, shortlength 2X4 liners arranged in face-toface contact with the oppositeinner surfaces of the chords, and also forming the vertical end supportsin double thickness 2X4 members and doubling the thickness of one of thetwo diagonal web members, whichever is the first tension loaded member,which are arranged between the doubled end portions of the chords. The2X4s on all the members are arranged horizontally, that is, their thinor narrow edges are in the vertical plane and their wide edges are inthe horizontal plane. Further, the doubled thickness members, beingunconnected to each other except along the vertical plane by means ofthe vertical arranged connector plates, have some limited movementrelative to each other to absorb stresses and strains and to avoid anytendency to crack or split lengthwise, thus forming a joist which may beof considerable length, yet of a high degree of stiffness and strengthwith minimal tendency to crack under varying loads.

Hence, an essential object of this invention is to form a truss-typejoist of considerable strength and rigidity yet of low cost usingreadily available and low cost 2X4 lumber.

Other objects and advantages of this invention will become apparent uponreading the following description, of which the attached drawings form apart.

DESCRIPTION OF DRAWINGS FIG. 1 is an elevational view of one end of thejoist. FIG. 2 is an enlarged, perspective view of the opposite end ofthe joist, and

FIG. 3 is an enlarged, fragmentary view of a section taken in thedirection of arrows 33 of FIG. 2.

FIG. 4 is an elevational view of the end portion of a modified joist.

DETAILED DESCRIPTION FIG. 1 illustrates a floor joist which is ofconsiderable length relative to its height. For example, typical sizeswould run approximately 24 feet long by 16 inches high or 28 feet longby 20 inches high or 32 feet long by 24 inches high. Obviously, thelength may be varied considerably whereas the height is relatively lowcompared to the length and varies only slightly despite increases oflength.

The joist is formed of an upper chord l l, a lower chord 12, with thechords interconnected by sets of alternating diagonally arranged webmembers 13 and 14 and by opposite end vertical end members 15.

As illustrated in FIGS. 1 and 2, the upper chord 11 is formed ofanouter, long 2X4 wood strip 17 having an inner, short 2X4 wood strip 18arranged in face-to-face contact at its opposite ends. Likewise, thelower chord 12 is formed of a long 2X4, outer wood strip 19 having itsopposite inner ends lined with a short 2X4 wood strip liner 20.

Each of the vertical end members 15 are formed of a pair of 2X4 woodstrips 21, arranged face-to-face. Also, the diagonal web member 14awhich is second from each of the opposite ends, and which is normallyunder tension, is formed of a pair of 2X4 wood strips 22 and 22aarranged face-to-face. In the event the joist is to be so loaded thatthe first web members 13a (the ones nearest to the joist ends) are to bein tension, then that first web member is formed of a pair of 2X4 woodstrips, instead of the second web members 14a.

As is illustrated in FIG. 2, all of the 2X4s are arranged on theirsides, that is, with their broad or wide faces in the horizontal planeand their narrow edges in the vertical plane.

The reference herein to 2X4 wood strips refers to conventional lumber,commonly called 2X4 meaning 2 inches by 4 inches in cross section, butactually of a slightly smaller size when the lumber is dressed. The sizeof the wood strips is not critical and may be varied somewhat but thesize herein referred to indicates the use of the conventionallyavailable inexpensive wood strips as contrasted with the previously usedlarge size wood beams which are relatively expensive, tend to crack andare not readily available.

The opposite ends of the web members abut the interior surfaces of thechords as does the opposite ends of the end members 15 to form jointswhich are connected by means of conventional, fiat sheet metal connectorplates of the type illustrated, for example, in the above-mentionedBroder US. Pat. No. 3,242,788-of March 29, 1966. These plates consist offlat sheet metal having struck-out teeth of suitable configuration forembedding into the wood.

FIG. 3 illustrates a corner joint wherein the plates 25, arranged oneach vertical face of the joint have their teeth 26 embedded into thechord strips 17 and 18 and into the vertical end members 21. The platesare typically secured into position by first arranging all the woodparts in their proper relationship, then placing the plates above andbelow the joints and squeezing them into the wood by meansof a suitablepress.

The size of the plates may vary, depending upon the size of the jointsand thus, large plates 24 may be used on most of the joints with smallerplates 25 at the joints of less area.

As described above, the double thickness portions of the chords, webmember 14a and end members 15 are so formed that the two strips makingup the double thickness are relatively movable to the extent that theyare not fastened face-toface but are fastened together only on theirvertical edges by means of the plates with the embedded teeth so thatthere is some degree of relative movement or relative buckling permittedbetween the double thickness members which functions to better absorbstresses and to yield thereunder and to avoid cracking or splittingwhich frequently occurs in heavier, prior types of wood beams. Thus, thedouble thickness members are for all practical purposes not securedtogether except at their ends and then only along their side or verticaledge faces so as to permit this relative movement or buckling.

However, for some constructions, it is desirable to anchor the doublethickness portions of the chord further for suitable strengthrequirements. Thus, FIG. 4 illustrates a modification wherein the upperchord is provided with an additional connector plate 28 at the free endof its inner or liner wood strip 18 and the lower chord is provided witha similar connector plate 29 midway between its ends. The inner andouter members of each chord are still free to move slightly relative toeach other particularly since they are secured together only along theirvertical faces by the embedded connector plate teeth.

vention, I now claim:

1. A floor joist comprising:

a pair of long, vertically spaced apart, parallel chords, each formed ofa long outer 2X4 wood strip and a pair of short inner 2X4 stripsextending from the outer ends from the long outer wood strip a shortdistance towards the center thereof, the inner strips being in looseface-toface contact with the respective outer strips to form doublethickness short end portions on each chord, and with the 2 4 strips alllaid on their sides so that their opposite narrow edges are vertical andcoplanar;

a vertical end member spanning the space between and endwise abuttingthe inner chord strips at each opposite end thereof; each end memberbeing formed of a pair of 2X4 wood strips arranged loosely togetherface-to-face with their narrow edges in the same planes as thecorresponding chord strip narrow edges;

sets of alternating diagonally arranged web members extending along thelength of the chord, with each web member diagonally spanning the spacebetween the chords and endwise abutting the opposed inner surfaces ofthe chords, and with each formed of a 2X4 wood strip having its oppositenarrow edges coplanar with the chord strip narrow edges;

a vertically arranged, flat sheet metal connector plate overlapping eachof the vertical faces of each joint formed between the web members andthe chord and the end members and the chord and secured to same byintegral struck-out teeth embedded therein for securing the members andchord together;

with the plates overlapping the end member joints also overlapping andsecuring the outer and inner chord strips together and the platesoverlapping the first set of web members closest to the end members alsooverlapping and securing the outer and inner chord strips together;

and the inner chord strips terminating only a short distance from saidfirst set of web members;

the pairs of strips forming the double thickness chord end portions andthe end members having their contacting faces free of securement to eachother and being slightly relatively movable for absorbing stresses andavoiding longitudinal splitting.

2. A floor joist as defined in claim 1 and wherein the first tensionloaded web member from each opposite end of the joist, that is, one ofthe two of the nearest set of web members to each opposite end which isto be loaded in tension, is formed of double thickness 2X4 wood strips,with the remaining web members being of single wood strips.

1. A floor joist comprising: a pair of long, vertically spaced apart,parallel chords, each formed of a long outer 2 X 4 wood strip and a pairof short inner 2 X 4 strips extending from the outer ends from the longouter wood strip a short distance towards the center thereof, the innerstrips being in loose face-to-face contact with the respective outerstrips to form double thickness short end portions on each chord, andwith the 2 X 4 strips all laid on their sides so that their oppositenarrow edges are vertical and coplanar; a vertical end member spanningthe space between and endwise abutting the inner chord strips at eachopposite end thereof; each end member being formed of a pair of 2 X 4wood strips arranged loosely together face-to-face with their narrowedges in the same planes as the corresponding chord strip narrow edges;sets of alternating diagonally arranged web members extending along thelength of the chord, with each web member diagonally spanning the spacebetween the chords and endwise abutting the opposed inner surfaces ofthe chords, and with each formed of a 2 X 4 wood strip having itsopposite narrow edges coplanar with the chord strip narrow edges; avertically arranged, flat sheet metal connector plate overlapping eachof the vertical faces of each joint formed between the web members andthe chord and the end members and the chord and secured to same byintegral struck-out teeth embedded therein for securing the members andchord together; with the plates overlapping the end member joints alsooverlapping and securing the outer and inner chord strips together andthe plates overlapping the first set of web members closest to the endmembers also overlapping and securing the outer and inner chord stripstogether; and the inner chord strips terminating only a short distancefrom said first set of web members; the pairs of strips forming thedouble thickness chord end portions and the end members having theircontacting faces free of securement to each other and being slightlyrelatively movable for absorbing stresses and avoiding longitudinalsplitting.
 2. A floor joist as defined in claim 1 and wherein the firsttension loaded web member from each opposite end of the joist, that is,one of the two of the nearest set of web members to each opposite endwhich is to be loaDed in tension, is formed of double thickness 2 X 4wood strips, with the remaining web members being of single wood strips.